Doped catalytic carbonaceous composite materials and uses thereof

Abstract

The present invention is directed to a composite material of a carbonaceous substance comprising a doped catalytic compound obtained by a sol-gel method. In one embodiment, the method comprises mixing a hydrolyzed solution comprising a precursor of a catalytic material with a carbonaceous material to obtain a sol. The sol is afterwards incubated while at the same time it is mixed. After incubation the sol is condensated to form a gel. After condensation the gel formed is subjected to a first calcination carried out in an oxidizing environment followed by a second calcination carried out in a non-oxidizing environment. The non-oxidizing environment comprises a second dopant comprising precursor material. Also, a solution of a first dopant comprising precursor material is added to the solution comprising an organometallic precursor of a catalytic material before hydrolyzation or before subjecting the gel to calcination, i.e. after hydrolyzation. In a further aspect, the present invention can refer to a method of removing pollutants comprised in a liquid stream by subjecting the liquid stream to a composite material described herein. In another aspect, the present invention is directed to a photocatalytic oxidation reactor comprising a composite material including a doped photocatalytic material.

1 . A composite material of a carbonaceous substance comprising a doped catalytic compound obtained by a sol-gel method comprising:
 mixing a hydrolyzed solution comprising a precursor of a catalytic material with a carbonaceous material to obtain a sol;   incubating the sol under mixing;   condensating the sol to obtain a gel-coated composite;   subjecting the gel-coated composite to a first calcination carried out in an oxidizing environment; and   subjecting the calcined gel-coated composite to a second calcination carried out in a non-oxidizing environment, wherein the non-oxidizing environment comprises a second dopant comprising precursor material;   
       wherein a solution of a first dopant comprising precursor material is added to the solution comprising an organometallic precursor of a catalytic material before hydrolyzation, or the first dopant comprising precursor material is added to the gel-coated composite before subjecting the gel-coated composite to calcination. 
     
     
         2 - 35 . (canceled) 
     
     
         36 . A sol-gel method for preparing a composite material of a carbonaceous substance comprising a doped catalytic compound, the method comprising:
 mixing a hydrolyzed solution comprising a precursor of a catalytic material with a carbonaceous material to obtain a sol;   incubating the sol under mixing;   condensating the sol to obtain a gel-coated composite;   subjecting the gel-coated composite to a first calcination carried out in an oxidizing environment; and   subjecting the calcined gel-coated composite to a second calcination carried out in a non-oxidizing environment, wherein the non-oxidizing environment comprises a second dopant comprising precursor material;   
       wherein a solution of a first dopant comprising precursor material is added to the solution comprising an organometallic precursor of a catalytic material before hydrolyzation, or the first dopant comprising precursor material is added to the gel-coated composite before subjecting the gel-coated composite to calcination. 
     
     
         37 . The method of  claim 36 , further comprising a process of repeated coating, wherein the process comprises:
 a) mixing a hydrolyzed solution comprising a precursor of a catalytic material and condensating it to obtain a gel;   b) adding a solution of a dopant comprising precursor material to the gel;   c) drying the gel-coated composite obtained directly after condensation but before calcination as referred to in  claim 36 ;   d) mixing the gel obtained in b) with the dried gel-coated composite of c) to obtain a repeatedly coated composite material;   e) drying the repeatedly coated composite material;   f) subjecting the repeatedly coated composite material to a first calcination carried out in an oxidizing environment; and   g) subjecting the calcined repeatedly coated composite material to a second calcination carried out in a non-oxidizing environment.   
     
     
         38 . The method of  claim 37 , wherein the process of repeated coating is carried out at least once using the dried repeatedly coated carbonaceous material obtained in a previous round under e) for mixing with the gel referred to under d) of  claim 37 . 
     
     
         39 . The method of  claim 36 , wherein the sol is heated for condensation. 
     
     
         40 . The method of  claim 39 , wherein the sol is gradually heated for condensation. 
     
     
         41 . The method of  claim 36 , wherein the oxidizing environment is an oxygen comprising environment. 
     
     
         42 . The method of  claim 36 , wherein the non-oxidizing environment is an inert atmosphere. 
     
     
         43 . The method of  claim 42 , wherein the inert atmosphere is nitrogen atmosphere or argon atmosphere. 
     
     
         44 . The method of  claim 36 , wherein the second dopant comprising precursor material is for the same or a different dopant than the first dopant comprising precursor material. 
     
     
         45 . The method of  claim 42 , wherein the second dopant comprising precursor material is comprised in the inert atmosphere in a mol % in relation to the inert gas of at most 50%. 
     
     
         46 . The method of  claim 36 , wherein the carbonaceous material is pre-treated with a basic solution. 
     
     
         47 . The method of  claim 36 , wherein the organometallic precursor is dissolved in an alcohol. 
     
     
         48 . The method of  claim 36 , wherein the first calcination is carried out at a temperature which is below the temperature used for the second calcination. 
     
     
         49 . The method of  claim 36 , wherein the first calcination is carried out at a temperature between about 400° C. to about ≦500° C. 
     
     
         50 . The method of  claim 36 , wherein the second calcination is carried out at a temperature between about >500° C. to about 700° C. 
     
     
         51 . The method of  claim 36 , wherein calcination is carried out for about 2 to 4 hours. 
     
     
         52 . The method of  claim 36 , wherein the first and second calcination are carried out independently of each other at a ramping rate of 5° C. to 10° C. per minute. 
     
     
         53 . The method of  claim 36 , wherein incubating the sol under mixing is carried out for a time period of between about 12 to 24 hours. 
     
     
         54 . The method of  claim 36 , wherein the carbonaceous material is a nanostructured carbonaceous material. 
     
     
         55 . The method of  claim 36 , wherein the carbonaceous material is activated carbon. 
     
     
         56 . The method of  claim 36 , wherein the activated carbon is in powder form. 
     
     
         57 . The method of  claim 36 , wherein the catalytic material is a photocatalytic material. 
     
     
         58 . The method of  claim 57 , wherein the photocatalytic material is selected from the group consisting of TiO 2 , ZnO, ZrO, CdS, MoS 2 , Fe 2 O 3 , SnO 2 , ZnS, W 2 O 3 , V 2 O 5  and SrTiO 3 . 
     
     
         59 . The method of  claim 36 , wherein the carbonaceous material is loaded with the doped catalytic material in an amount of between about 10 wt. % to about 50 wt. %. 
     
     
         60 . The method of  claim 36 , wherein the dopant is a non-metal dopant. 
     
     
         61 . The method of  claim 60 , wherein the non-metal dopant is selected from the group consisting of nitrogen, halogen, sulfur, and phosphor. 
     
     
         62 . The method of  claim 36 , wherein the dopant comprising precursor material is selected from the group consisting of NH 3 , urea, NH 4 OH, hydrazine, amine, thiourea, carbon disulfide, iodic acid, sodium hypophosphite and hypophosphorous acid. 
     
     
         63 . The method of  claim 36 , wherein the precursor of a catalytic material is a metallic alkoxide or an organometallic precursor. 
     
     
         64 . The method of  claim 36 , wherein the molar ratio of precursor of a catalytic material to first dopant comprising precursor material is in the range of 1:10.